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Reading data

In this part of the tutorial, you will experiment with reading a seismic dataset in SU format, converting it to RSF format, examining its values, and displaying it on the screen. You are asked to answer a series of simple questions. Insert your answers by editing the nankai/paper.tex file.

  1. Change directory to nankai/data.
  2. Run
    scons -c
    
    to remove (clean) previously generated files.
  3. Run
    scons shots.rsf
    
    This command will find the SU file for the Nankai data and convert to two files: trace header data (tshots.rsf) and trace data (shots.rsf).
  4. Examine the trace data file shots.rsf by running
    more shots.rsf
    
    What is the data format used in this file? How many traces does this file have (n2= parameter)? How many time samples per trace (n1= parameter)?

    \fbox{\parbox{\boxwidth}{\textbf{Answer:}
}}

    Note that a more convenient way to check parameters is running a Madagascar program sfin:

    sfin shots.rsf
    
  5. Examine the range of values in the trace data file by running
    sfattr < shots.rsf
    
    What is the maximum value? How many zero samples are in this file?

    \fbox{\parbox{\boxwidth}{\textbf{Answer:}
}}

  6. Run
    scons shots2.view
    
    to display all shot gathers in the Nankai dataset. Some traces are missing. To view the mask of the missing traces shots, run
    scons smask.view
    
    and observe where missing traces are located.

  7. Examine the content of the trace header file tshots.rsf by running
    sfheaderattr < tshots.rsf
    
    To get a short description of different keys, you can also run
    sfheaderattr < tshots.rsf desc=y
    

  8. Run
    scons shot.view
    
    to window and display traces corresponding to the 1707th shot record (Figure 1).
  9. Run
    scons offset.rsf
    
    to window values of offset (receiver-shot distance) for the 1707th shot record. Examine the values by running
    sfdisfil < offset.rsf
    
    What is the offset for the receiver closest to the source? What is the distance between receivers?

    \fbox{\parbox{\boxwidth}{\textbf{Answer:}
}}

    shot
    shot
    Figure 1.
    Wiggle plot of the 1707th shot record from the Nankai data.
    [pdf] [png] [scons]

  10. Open the SConstruct file in your favorite editor and find the command which windowed the 1707th shot record. Change it to window different shot records. Run
    scons shot.view
    
    again to see the effect of the change. Edit the plot title to reflect the change.


next up previous [pdf]

Next: Frequency filtering Up: 2-D Seismic Data Processing Previous: Generating this document

2016-06-07